The NTPC initiated a probe to ascertain the reasons behind the blast while Chief Minister Yogi Adityanath announced Rs 2 lakh compensation for the families of those killed and Rs 50,000 for the grievously injured, they added.
"Eighteen deaths have been confirmed by the district administration. Twenty two persons with severe burns have been referred to Lucknow. Another 15 are in Rae Bareli hospital," UP's ADG (Law and Order) Anand Kumar said.
Principal Secretary (Home) Arvind Kumar said that 90-10 persons had been injured in the blast.
In a statement, the NTPC said that at around 1530 hrs at unit number six of its Unchahar plant, there was a sudden abnormal sound at 20 meters elevation.
More From This Section
There was an opening in corner number two from which hot flue gases and steam escaped affecting the people working around the area, the central public sector undertaking said.
It added that around 80 people were rushed to NTPC hospital, most of them were discharged after giving first-aid.
The Unchahar sub-division in Raebareli district is around 110 km from the state capital.
ADG Kumar said that all available ambulances were pressed into action and the additional district magistrate and the additional superintendent of police were on the spot to supervise relief and rescue operations.
Chief Minister Adityanath, who was away in Mauritius on a three-day official visit, ordered that necessary steps be taken for rescue and relief.
"The chief minister expressed his condolences over the deaths of workers in the Unchahar NTPC unit and announced Rs 2 lakh compensation for the family of those killed and Rs 50,000 for the grievously injured besides Rs 25,000 for other injured workers," Awasthi said.
A National Disaster Response Force (NDRF) team was also despatched to the explosion site from the state capital for relief and rescue operations, an official said.
Such explosions can generate searing heat, an official said.
An injured employee undergoing treatment at a hospital said that a sudden gush of hot gas with contents of ash-like material engulfed him at the NTPC plant.
The man said he was unable to understand what had happened and found himself on a hospital bed with his body scalded all over, when he regained consciousness.
The plant area was cordoned off by the police to facilitate smooth running of ambulances.
Congress president Sonia Gandhi expressed shock and horror at the "terrible tragedy" in her Lok Sabha constituency Raebareli. Conveying her deepest condolences to the families of the bereaved, Gandhi urged upon the authorities to provide immediate medical assistance to the injured.
Chief Medical Officer, Raebareli, DK Singh along with a team of ten doctors were deployed to carry out immediate treatment to the injured, he said.
He also said that arrangements have been made to bring the serious cases to KGMU hospital and the civil hospital in Lucknow. Some of the injured were being sent to Raebareli, Khatri said.
CMO Singh said that if necessary some of the critical cases could be referred to Delhi by air ambulance.